Hi it's a great place to stay, we launched the sib one day out of 5 in April last year due to the weather from the slip on the site, it's not run by haven but will give a discount, beware though there are some really shallow bits just off the channels there as we went off we could see the bottom for quite a while! It cost us ₤12 to launch I think.

Enjoy the site it's a nice one and pay a visit to Georgie porgies in Poole and the swimming pool next door well worth a visit if the weather is playing up!

As mentioned in the previous comment, stay well within the markers in Poole Harbour, especially in the narrow channels and creeks. Many of these are dredged to the width of the markers, so veering even 1ft outside them could ding your prop or, worse still, leave you beached on a steep bank. This is still a risk irrespective of tide height in some places.
So, keep within the marked channels and have a great weekend, the harbour is a wonderful place to explore.

If its only a small rib and you can hand lauch it theres a free public slipway at the bottom of lake road in hammworthy. I launch my thundercat by hand from there with ease and ive managed to launch it at all tide states so you dont have to worry about tide. The only restrictions are it has to be less than 6ft 1" wide (i think) Mine just squeezs through so should be fine!